Downdraft stove



v April 27, 1954 E. J. BLUMSON DOWNDRAFT STOVE F:i .led March 8, 1949 5Sheets-Sheet 1 V E. J. BLUMSON A April 27, 1954 DOWNDRAFT STOVE 5Sheets-Sheet 2 Filed March 8, 1949 April 27, 1954 E. J. BLUMSON 76,

' DOWNDRAFT' STOVE Filed March a, 1949 5 Sheets-Shed a i E. J. BLUMSONApril 27, 1954 DOWNDRAFT' STOVE 5 Sheets-Sheet 4 Filed March 8, 1949 5Sheets-Sheet 5 Filed March 8, 1949 Patented Apr. 27, 1954 DQWNDRAFTS'IQXZ-E 'Ernest" James Blumsom, London,"Ei1gIand," as

signorto Allied lronfounders'liimitedi Ii'ondon; England; a-British'company-= Application; March 19% Seriab N o. 80,26:3.

Claimepriority; application Great Bi-itain -March 165 194.8

This invention relates to.- stovesaofi'theakindin which: a fuel' hopperxtendsz upwardly from-5a combustion" zoneto-which solid fuel contained.the hopper feeds by gravityaandiinwhichr'the whole of the primary. airfor" combustion? passesdownwardly through. the? column offuel.maintained' in the hopperto the combustion zone, while secondary air isadmixed.withtheproducts of combustion-passing: from the combustionv zoneto effect complete combustion. of the smoke and/or:soot-formingproducts.

In constructions 1 of stoves" off this kind heretoforev proposed; theprimary air" andrsecondary air" areadmitted to the; stove structurethrough separate iniets which: are separatelycontrollable;

The rate-- of combustion of the stove is deterrminedbycontrolof theinlet for primary air; and the inlet=:f .or secondary-"air is:separateiycontrol:- lablev to achievev the desirediconditions of.cornpletea combustion;

The present invention has for'its object-taprovide' an improved!construction of stoveofthe kind referred? to; wherein any fi1el,: butinparticular: bituminous coal or other highly volatile solidi fue1,-may beburned: with. a: minimum: of

smoke or soot, and in general moreefficient:come bustion may be obtainedwithout the necessity of relative adjustmentizofseparate-airritriets:according: to the: desired rate: of? combustion;

According to the: present: invention, imaa stove of the kind referredto; aii -iszadmittedhthrough a singlecontrollables-airz inlet to achamber below the grate-cor" other. fuel support;- in: which. chamber:it' is pre-heated and: from which; it: dis tributed": in proportions:determined? by: the relaz tive crossssection'of"distributing'rpassagesonfiowcontrolj; openings therein: toasupplyrthe: primary air; tow the; top of: thehopper and the. secondaryair to the products of combustion passing from the"zoneeoicombustion;

In one embodiment the air is admitted: ton-and 'distributed"from= an:ashpit: chamber: disposed below an-imperforatezfuel support structure;The

imperforate fuel support" structure may be mounted-tobecapableofreciprocatiomunden the control of external actuating meanscounterrweighted flap members-being arranged soas to seal ash outletpassages between lateraledgesof the fuel support structure 'and theadjacent structureof'the'stove. I

In: anotherenrhodimerit; a; perforatevgiate structure is-utili/'zer11"in' conjunctiona sealed ashpit preventing access" of" air;thereto. and." the air. isadmittedito and-distributedf from. a: cham.-'ber extending around'the aslipit;

vent entry-of air,- counter-weighted flaps 2d, are

ment:

may be agitatedby-a to and fro movement.

or substantial thickness;

"Theinventionw isaliereinafter' described, by way ofwfexampleyv with:referenceito the accompanying diagrammaticdrawings; which- Fig.- 1--isnazsectional side: elevation: illustrating a continuous combustionconvection heaterv'constructedi in: accordance with the presentinvention;.

Fig is a; sectional 'front elevation correspondingtoFig. 1';-v

. Fig. 3iis-a sectiononthelineIIL-III of Fig; 2;

Fig; 4 is a. view: similarrt'o: Fig: .1- illustrating a modification;and

Fig: 5' is aisectional front elevation correspondingztot Fig: 42

Irv-carrying the invention into efi'ect according to: one-embodiment,-and -w-ith reference to' Figs.

1. to 3 of thetaccompanying" diagrammatic drawings;a..'continuous1burning convection heater comprises. axverticallydisposedchamber I. of

rectangular: OIfOSSF SGCtlOH forming" a fuel hopperin-whiclrisiaestablished a column of fuel'that feeds progressivelydownwarwto a combustion zone l w locatediat-zthe lower end of 'thechamber l said chamben'beingprovided with a. door la at the front foracharging the' hopper; and a flat roof lb healer prod ecting: teetlr. 2e01" the like which v slide overrsimilan-memhers i I projecting from; anad'- jacentt, part? of. the stove; the structure thereby providhigugridsfor ash riddling. In order that the" ash outieta may be. normally:sealed to prearranged to contact the lower'edge' of the fuel support iand of' the a'djacent'xpart of the stove structure when the-fuel support2 isin the intermediatez'position' between the limits of its move- The'-sidewalls' lc' of the chamber i are constituted oyslabsof-suitabierefractory material At the outer side of these; refractory;side; walls [0, channels Id are provided, saidhhannels' i at beingcoveredfby plates 4 :50 as to form'tverticall fiues 5"=which'communicate atia vsuitable:hei'ghtlabove thegrate 2 with the" combustionzone through inlets 521. At the the hot zone Ida of the fire. secondaryportion of the air from the ashpit 3 also passes up through the passagesNa and II top the said flues 5 communicate with a passage 6 extendingover the roof Ib and leading to a flue I communicating with a chimneyoutlet 8.

The rear wall Ie of the chamber I, which wall also may be of refractorymaterial, has an outer wall 9 spaced therefrom to provide an upwardlyextending primary air duct It at the back of the chamber I and extendingthe full width thereof. This duct Ill at the botom communicates with theashpit 3 below the fuel support 2 and the rear wall Ie of the chamber Iextends short of the top of the side walls Ic so that the duct I is incommunication with the chamber I at its upper part. Passages I la forsecondary air also extend upwardly from the ashpit 3 and. communicatewith passages II disposed externally of inclined walls Ig defining thecombustion zone and leading through openings I2 to the fines 5, theopenings I 2 in this embodiment being suitably positioned above theinlets a from the combustion zone so that the secondary air from thepassages I I is introduced at zones which normally are incandescent,thereby ensuring complete combustion of volatile or smoke andsoot-forming products.

In accordance with this invention all of the primary air for combustionwith the solid fuel and all of the secondary air for ensuring completemounted on an ashpit door Sb. A primary portion of this air passesthrough the duct I 9 behind the chamber I to the top of the chamber andthence downwardly through the fuel it so as to carry volatile productsof combustion to or into Furthermore, a

to the fines 5, the primary and secondary portions of the air beingdistributed on these two main paths in suitable proportion by suitabledetermination of the relative cross-section of the respective airpassages or of flow control openings associated therewith at anysuitable point.

In the modification illustrated in Figs. 4 and 5, the generalconstruction of the stove is similar to that shown in Figs. 1 to 3except that the plates ll of Fig. 2 are replaced by refractory slabs 4a.

til

grate bar structures 2e, 2 may be relatively movable by any suitablemeans for eifecting ash riddling.

In both embodiments, in order to obviate outrush .of flame or smoke whenthe door la is opened for charging the hopper, a valve plate I5 issupported by means of cams IEia mounted upon or operated by a lockinghandle I6 on the door Ia so that when the handle It is turned to unlockthe door la, the valve member I5 is permitted to drop so as to open anoutlet I9 and thus establish direct communication between the upper partof the chamber I and the through passage 6 across the top thereof beforethe door Ia is opened.

The stove structure is enclosed in an outer casing l1 providing airpassages Ila for convection currents, said passages Ila having inletsill? at the bottom and outlets Ilc at the top. The upper part Ild of thecasing may have an opening Ile and the top We of the stove structure maybe provided with fins lm for more effective radiation of heat therefrom.As shown more particularly in Fig. 3 the side walls in of the stovestructure may be provided with fins I2 Instead, however, of providing animperforate fuel support structure for preventing passage of airupwardly through the fuel supported thereon, a perforate grate structuris provided comprising grate bars 2c, 2) fixed on cross members 29,

21?. respectively, said cross members being supported on fixed members21', and in order to prevent upward flow of air through the fuel on thegrate, said grate is enclosed in a sealed ashpit 3 having side walls Ir,a rear wall Is, bottom wall lo and removable front panel It, the latterbeing held in place by suitable means, such as a spring Isa associatedwith the damper I3 on the door 31). This construction of ashpit providesan air passage I I0 at the front extending downwardly from the damperIS, an air passage I Ib extending beneath the ashpit, air passages Haextending up the sides of the ashpit, and at the rear a direct from thepassages H are disposed in the inclined walls Ig and communicate withzones in the vicinity of the inlets 5a to the fines 5. The two It willbe understood that, owing to the arrangement of the air passages in oradjacent walls of the vertical chamber, the air supply is effectivelypre-heated.

Furthermore, it will be understood that the invention is not limited toth particular embodiment hereinbefore described. For example, instead ofthe air passages iI extending upwardly from the ashpit 3 to the fines 5,they may extend downwardly from the upper part of the air duct It sothat in effect the subdivision of the air supply takes place at theupper part of the chamber i. Moreover, the grate may be of conventionalconstruction so that the air supply is distributed in three paths, i. e.upwardly through the grate in addition to the two main paths beforereferred to.

Furthermore, it will be understood that the invention is applicable toother constructions of stoves of the kind referred to, and thearrangement and disposition of the air passages may be modified invarious ways.

I claim:

1. A magazine-feed solid fuel burning stove of the down draft typecomprising an upright chamber constituting a hopper for receiving acolumn of the fuel, a support at the lower end of said chamber for thelower end of the fuel column to establish a combustion zone in the fuelcolumn limited to the lower part thereof on the support, wall membersforming an air distributing chamber beneath said fuel support,adjustable air inlet means to said distributing chamber through whichthe entire air for the stove passes, means pre venting air flow upwardlythrough said fuel support into the combustion zone, air passagewaysextending from said distributing chamber to the top of said uprightchamber through which the whole of the primary air for combustion passesupwardly and thence downwardly through the column of fuel in saidupright chamber to the combustion zone, exhaust passageways leading fromsaid combustion zone to the exterior of said stove through which theproducts of combustion are conveyed, and passageways leading from saiddistributing chamber to the vicinity of the entrance ends to saidexhaust passageways for introducing secondary air for burning off anyunburned combustible products entering said exhaust passageways.

2. A magazine-feed stove as defined in claim 1 wherein said fuel supportis imperforate, being provided with normally closed ash outlet passagesbetween lateral edges of said fuel support and adjacent members of thestove, and said air distributing chamber comprises an ashpit disposedbelow said fuel support and ash outlet passages, said ashpit beingnormally walled-off from said combustion zone.

3. A magazine-feed stove as defined in claim 2 wherein said imperforatefuel support is provided with means whereby the same may be reciprocatedand wherein counter weighted flap members are used to normally close oilsaid ash outlet passages.

4. A magazine-feed stove as defined in claim 1 wherein said fuel supportis performated, an ash pit disposed beneath said perforated fuel supportnormally communicates with said combustion zone, said ash pit beingsealed against entry of air, and said air distributing chamber extendsaround said ash pit.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 231,163 Hamlin Aug. 17, 1880 573,170 Watson Dec. 15, 1896603,967 Piron May 10, 1898 725,228 Deprez et al. Apr. 14, 1903 2,399,814Martin May 7, 1946 FOREIGN PATENTS Number Country Date 224,116 GermanyJan. 10, 1910 422,302 France Jan. 16, 1911 50,816 Norway May 9, 1932808,783 France Nov. 24, 1936

